摘要:
A method of directly softening a rolled machine structural steel is provided. This method is characterized by the fact that it comprises the steps of:hot rolling a steel consisting essentially of 0.2-0.65% C, less than 0.1% Si, 0.2-0.5% Mn, 0.0003-0.01% B, more than 0.5-1.7% Cr, 0.01-0.1% Al, all of the percentages being on a weight basis, and the balance being Fe and incidental impurities, and may contain one or more other alloying elements selected from either one of or both of groups (A) and (B), group (A) consisting of not more than 1% Ni, 0.1-0.5% Mo and not more than 1% Cu, and the other group (B) consisting of 0.002-0.05% Ti, 0.005-0.05% Nb and 0.005-0.2% V,then subjecting said rolled steel to either one of the two softening treatments (1) or (2), the treatment (1) comprises slowly cooling the steel in a temperature range until transformation to pearlite is completed at a cooling rate of less than 15.degree. C./min, and the treatment (2) comprises, isothermally holding said steel in a temperature range of 680.degree. to 730.degree. C. until the transformation to pearlite is completed and then to natural cooling, so that the steel can display a tensile strength less than a value expressed by a formula,24+67.times.Ceq (kg/mm.sup.2), specified by the carbon equivalent Ceq (kg/mm.sup.2) of the subject steel.
摘要:
A method of softening a rolled medium carbon machine structural steel is provided. This method is characterized by:(1) hot rolling steel containing 0.32-0.65% C, less than 0.05% Si, 0.3-0.9% in total of Mn and Cr, with the Mn and Cr contents being 0.2-0.5% and 0.1-0.5%, respectively, 0.005-0.1% Al, less than 0.02% P and less than 0.02% S, all percents being on a weight basis, and the balance being Fe and incidental impurities; and(2) performing either one of the following softening treatments:(i) slowly cooling the as-rolled steel at a cooling rate of 3.degree.-30.degree. C./min over the temperature range of from 750.degree. C. to the point where transformation to pearlite is completed to thereby provide the rolled steel with a strength of not greater than 30+65.times.C % (kg/mm.sup.2), C % signifying the carbon content of the steel; oras-rolled quenching the hot rolled steel to a temperature within the range of 670.degree.-720.degree. C., holding the steel in this temperature range for 4-60 minutes, and then air-cooling the steel to thereby provide the rolled steel with a strength of not greater than 30+65.times.C % (kg/mm.sup.2), C % signifying the carbon content of the steel.
摘要:
A high-strength, ultra-fine wire having an excellent workability in stranding, comprising a steel comprised of, in terms of % by weight, 0.85 to 1.10% of C, 0.10 to 0.70% of Si, 0.20 to 0.60% of Mn, 0.10 to 0.60% of Cr, 0.005% or less of Al and optionally at least one member selected from 0.10 to 2.00% of Ni and 0.10 to 3.00% of Co with the balance Fe and unavoidable impurities and, provided thereon, a brass plating, the steel wire having a diameter of 0.1 to 0.4 mm and a tensile strength of 400 kgf/mm.sup.2 or more, the surface of the brass plating being provided with indentations having a depth of 2 .mu.m or less at intervals of 50 .mu.m or less in a percentage area of indentations of 10 to 80%; and a process and apparatus for producing a high strength, ultra fine steel wire, comprising subjecting a steel wire material to a patenting treatment, brass plating and wire drawing and subjecting the steel wire material to a shot peening treatment in an air blast system while applying a tension to the steel wire material.
摘要:
The invention provides a steel material with satisfactory hydrogen embrittlement resistance, and particularly it relates to high-strength steel with satisfactory hydrogen embrittlement resistance and a strength of 1200 MPa or greater, as well as a process for production thereof. At least one simple or compound deposit of oxides, carbides or nitrides as hydrogen trap sites which trap hydrogen with a specific trap energy is added to steel, where the mean sizes, number densities, and length-to-thickness ratios (aspect ratio) are in specific ranges. By applying the specific steel components and production process it is possible to obtain high-strength steel with excellent hydrogen embrittlement resistance.
摘要:
Steel and steel shaped articles with an excellent delayed fracture resistance and a tensile strength of the 1600 MPa class or more, containing, by mass %, C: 0.20 to 0.60%, Si: 0.50% or less, Mn: over 0.10% to 3%, Al: 0.005 to 0.1%, Mo: over 3.0% to 10%, and, as needed, one or more of W: 0.01 to 10%, V: 0.05 to 1%, Ti: 0.01 to 1%, Nb: 0.01 to 1%, Cr: 0.10 to 2%, Ni: 0.05 to 1%, Cu: 0.05 to 0.5%, and B: 0.0003 to 0.01%, and a balance of Fe and unavoidable impurities and, further, a method of production comprising shaping the above steel to a desired shape (for example, a bolt shape), quenching it, then tempering it at 500 to 750° C. in temperature range.
摘要:
The invention provides a steel material with satisfactory hydrogen embrittlement resistance, and particularly it relates to high-strength steel with satisfactory hydrogen embrittlement resistance and a strength of 1200 MPa or greater, as well as a process for production thereof. At least one simple or compound deposit of oxides, carbides or nitrides as hydrogen trap sites which trap hydrogen with a specific trap energy is added to steel, where the mean sizes, number densities, and length-to-thickness ratios (aspect ratio) are in specific ranges. By applying the specific steel components and production process it is possible to obtain high-strength steel with excellent hydrogen embrittlement resistance.
摘要:
A saw wire includes a steel wire (11) having a steel strand (11a) with predetermined composition, an abrasive (13) fixed to the steel wire (11) by a fixing part (12), and an intermetallic compound (15) on an interface between the abrasive (13) and the fixing part (12). Tensile strength of the steel strand (11) is 3500 MPa or more, and the fixing part (12) includes a Sn-based solder containing Zn or Ag.
摘要:
The invention provides a steel material with satisfactory hydrogen embrittlement resistance, and particularly it relates to high-strength steel with satisfactory hydrogen embrittlement resistance and a strength of 1200 MPa or greater, as well as a process for production thereof. At least one simple or compound deposit of oxides, carbides or nitrides as hydrogen trap sites which trap hydrogen with a specific trap energy is added to steel, where the mean sizes, number densities, and length-to-thickness ratios (aspect ratio) are in specific ranges. By applying the specific steel components and production process it is possible to obtain high-strength steel with excellent hydrogen embrittlement resistance.
摘要:
The present invention provides a high strength bolt excellent in delayed fracture resistance able to advantageously prevent hydrogen embrittlement as represented by the delayed fracture phenomenon occurring along with an increase in strength and causing a particular problem, and a method of production of the same, containing, by mass %, C: 0.2 to 0.6%, Si: 0.05 to 0.5%, Mn: 0.1 to 2%, Mo: 0.5 to 6%, and Al: 0.005 to 0.5%, having a tensile strength of 1400 MPa or more, and having a compressive residual stress of the surface layer of the thread root of 10 to 90% of the tensile strength. Further, a surface layer part of the thread root from the surface down to at least 50 μm has pre-austenite grains with an aspect ratio of the axial direction and radial direction of 2 or more and that part has a hardness of Hv 460 or more. Further, the method of production comprises using the steel material having the above ingredients to shape the bolt head and shaft, then heat the bolt to 900 to 1100° C., quench it, temper it by a 580° C. or higher temperature, then thread roll it.
摘要:
The present invention provides a high strength bolt excellent in delayed fracture resistance able to advantageously prevent hydrogen embrittlement as represented by the delayed fracture phenomenon occurring along with an increase in strength and causing a particular problem, and a method of production of the same, containing, by mass %, C: 0.2 to 0.6%, Si: 0.05 to 0.5%, Mn: 0.1 to 2%, Mo: 0.5 to 6%, and Al: 0.005 to 0.5%, having a tensile strength of 1400 MPa or more, and having a compressive residual stress of the surface layer of the thread root of 10 to 90% of the tensile strength. Further, a surface layer part of the thread root from the surface down to at least 50 μm has pre-austenite grains with an aspect ratio of the axial direction and radial direction of 2 or more and that part has a hardness of Hv 460 or more. Further, the method of production comprises using the steel material having the above ingredients to shape the bolt head and shaft, then heat the bolt to 900 to 1100° C., quench it, temper it by a 580° C. or higher temperature, then thread roll it.